1. Technical Field
This disclosure relates to current mode switching power supplies and to controllers that regulate them.
2. Description of Related Art
Switching power supplies may control their output with a constant frequency switching signal that is periodically turned off when current in an output stage reaches a threshold level. Positive slope compensation is sometimes added to prevent undesirable sub-harmonic oscillation when operating at switch signal duty cycles above 50%.
However, positive slope compensation can reduce the output impedance of the switching stage averaged over each switching cycle. This may cause the output inductor to introduce a phase shift in the feedback loop. In turn, this may reduce the phase margin of the feedback loop which may lead to poor transient response or even feedback loop instability.